1. Field of the Invention
The present invention relates to an electronic equipment as an electronic equipment system apparatus main body having a plurality of optional apparatuses connected to an apparatus main body through a bus, an optional apparatus, and an image forming apparatus.
2. Description of the Related Art
Generally, an image forming apparatus such as a printer includes an image forming section which forms an image on a sheet and a sheet tray which supplies the sheet to the image forming section. In many cases, a plurality of sheet trays are stacked for use in accordance with a user's demand. In such case, an apparatus main body having an image forming section and each of the sheet trays are connected through a bus line, and a command signal is transmitted from the apparatus main body so that driving of each sheet tray is controlled.
In particular, the bus line has a select line and a serial line, and any one sheet tray is selected by the select line from among the plurality of sheet trays. The selected sheet tray accepts the command signal transmitted through the serial line and executes a processing in accordance with the command signal.
Further, as disclosed in Japanese Patent Unexamined Publication No. Hei 3-265059 and Japanese Patent Unexamined Publication No. 2000-315277, there are the cases where a command signal is transmitted in a simultaneous communication from an apparatus main body to all of sheet trays (optional apparatuses).